Abstract: An adjustable clamp for clamping a work piece in a T slot of the bed plate of a machine tool. The clamp comprises a one piece rocker body with a work engaging portion at one end to hold down a work piece. The lower center of the clamp has a fulcrum portion of less width than the T slot and pivotally connected below the bedplate which anchors the clamp thereto. The other end of the clamp has a thrust screw which enters the T slot in the bed plate. A pair of oppositely projecting studs, each with a curved upper surface, enable the clamp to rock in the T slot, when the thrust screw is tightened, to firmly lock the work piece on the bed plate.